Anal fistula is an abnormal channel formed by the anal canal or rectum with the adjacent tissues and organs around the anus for pathological reasons. It is a common disease, usually formed by the infection of anal glands with pus to form a perianal abscess, and after the abscess breaks or is incised, the wall of the growing canal forms a fistula; there are also a few cases formed by the collapse of a perirectal abscess complicated by other diseases, such as ulcerative colitis.
I. Etiology.
The reason for anal fistula, according to the ancestral medicine, is not only internal injury, external infection, unclean diet, long illness and loss of glory, so that the body’s yin and yang is not harmonious, and the customs of the yongsei, Qi and blood do not run smoothly, so that the evil can take advantage of the deficiency to stay injected into the large intestine, so that the evil poison injury in the internal, set into poison, poisonous evil long depression, depression and heat, heat rot into pus, through the intestine through the buttocks, so trickle into fistula, indicating that the ancients noted the relationship between local lesions and the whole, reflects The objective law that internal causes are the basis for change and external causes are the conditions for change is consistent with clinical reality.
The cause of anal fistula is mainly bacterial infection, the site of bacterial invasion is the anal fossa, anal gland ducts and anal glands, the anal gland infection and pus can flow around the anorectum or linger under the intestinal mucosa, when the abscess is self-collapsed or cut open to drain the pus, anal fistula caused by anal gland infection accounts for 95-97%, only a few cases due to ulcerative colitis, Crohn’s disease, multiple There are only a few cases caused by ulcerative colitis, Crohn’s disease, multiple purulent sweat glands, and a few cases caused by rectal injury, inappropriate withered hemorrhoids, etc.
Second, the anal glands.
1.What is anal gland?
Anal gland: also called anal duct, intramuscular gland, deep rectal gland. It has a wide range of individual differences in form, number, structural style and distribution. In adults, there are 4-10 anal glands, usually no more than 8, and in newborns, up to 50, located in the submucosa or internal sphincter of the lower pectineal region of the anal fossa, sometimes reaching the joint longitudinal muscles.
The opening of the anal glands: sometimes, one anal gland opens in one anal saphenous fossa, or two anal glands open in the same saphenous fossa. Not all fossae are connected to the anal glands, and about half of the fossae do not have an opening for the anal glands. Very few anal glands can open directly into the anal canal and rectum.
2. Location and course of anal glands.
(1) Most anal glands are concentrated in the posterior part of the anal canal.
(2) In adults, the anal glands are mainly concentrated in the posterior part of the anal canal, with fewer glands on both sides and almost no glands in the anterior part.
(3) The anal glands are scattered around the anal canal.
(4) The opening of the anal glands and the anal ducts are on the same vertical line (the line between the dentary line and the anal ducts) in 65% of cases and not on a vertical line in 35% of cases, with 68% of the ducts below the dentary line, 28% above the dentary line and 4% across the dentary line.
3, the debate on the anal gland – the nature of the anal gland.
One opinion is that the anal gland is a degenerate tissue without secretory function, a residue of the embryonic development process, and has no functional significance.
Another opinion is that the anal gland exists in all periods of human embryonic development and is an independent structure that maintains its secretory function as a gland for life.
4. The clinical significance of the anal glands.
(1) The anal gland is the general source of all perianal disorders.
(2) 95% of all anal fistulas originate from anal gland infection.
(3) The importance of the anal glands in physiology, pathological anatomy and perianal infections is undeniable.
5. Functions of the anal glands.
(1) To assist in defecation.
(2) Protect the anal canal.
III. Anal fistula.
1. Pathology.
The formation and development of abscesses can be divided into the following stages.
(1) Early bacterial invasion stage.
(2) Pus formation stage.
(3) The stage of fistula formation.
(4) As a whole, an anal fistula generally consists of four major parts: the internal port, the main port, the branched port, and the external port.
2. Classification of anal fistula.
The classification criteria for anal fistulas developed by the Chinese Society of Traditional Chinese Medicine, Anal Branch in 2002 are
(1) low anal fistula.
Low simple anal fistula; low complex anal fistula.
(2) High anal fistula.
High simple anal fistula; high complex anal fistula.
3. Clinical symptoms.
(1) Pus flow.
(2) Pain.
(3) Anal wetness and itching.
(4) Hard strip-like swelling at the anal margin.
(5) Systemic symptoms.
4. Examination – Determine the location of the internal orifice.
(1) The location of the internal orifice can be determined from the medical history.
(2) Palpation can help to understand the location of the internal orifice.
(3) The location of the internal orifice can be determined by the distance between the external orifice and the anal opening.
(4) Solomons’ law can help to diagnose the internal orifice.
(5) Probe examination.
(6) Anoscopy.
(7) Staining examination.
(8) Iodine oil imaging, endorectal ultrasound and intraoperative exploration.
(9) MRI (magnetic resonance imaging) and spiral CT three-dimensional reconstruction.
(5) Determine the depth of the fistula in relation to the sphincter.
Since the tube of anal fistula passes through the external sphincter or anal raphe, and sometimes the tube travels between the internal sphincter, incision of the tube during surgery must necessarily cut through the relevant anal sphincter, especially for fistulas that pass through the anorectal ring, and incision of the anorectal ring can cause anal incontinence after surgery.
6, the diagnosis of anal fistula.
The main lesion must be understood. The examination of anal fistula cannot be localized, but must be analyzed comprehensively in order to make a correct diagnosis. First, the scope of the lesion is understood from the appearance of the anus; second, the depth of the lesion, the relationship between the direction of the canal and the anal sphincter, and the location and number of internal ports are understood from the frontal plane; and again, the relationship between the lesion and the front and back of the rectum is understood from the sagittal plane.
7. Systemic examination.
Although the lesions of anal fistula are localized, systemic examination should never be neglected, especially for those with unclear internal orifices, attention must be paid to the presence of lesions in the presacral area. In particular, we should be more cautious about complex anal fistulas, and if necessary, we can do bacterial culture and antibiotic sensitivity test, pay attention to blood sedimentation, blood picture and anal sphincter function measurement, and in some suspicious cases, biopsy can be done to determine the nature of the anal fistula, and we should especially observe whether there is cancer.
8. Differential diagnosis.
(l) Perianal septic disease.
(2) Sacrococcygeal fistula.
(3) Sacrococcygeal teratoma.
(4) Sacroiliac tuberculosis.
9.Diagnostic hints.
(1) The presence of anal fistula can be considered when there is a history of perianal abscess and the wound does not heal with repeated swelling and pain and pus flow after self-rupture or abscess incision. The external opening is often around the anus or any part of the buttocks, forming a depression or a protrusion on the skin surface, with pus overflowing when pressed, and the surrounding skin is often peeling due to pus and secretion stimulation, sometimes with granulation tissue protruding from the internal opening.
(2) Tuberculous anal fistula, with a large external opening, uneven shape, sunken edges, yellowish surrounding skin, thin secretions, and non-hard walls.
(3) Low-grade anal fistula can be palpable under the skin with hard strips of cords from the external orifice to the anus, with pus overflowing from the external orifice when lightly pressed with the finger.
10.Diagnostic hints.
(1) high anal fistula, there are hard scar near the rectal ring of the anal canal, mostly in the posterior and both sides, there are also large scar in the sciorectal fossa, sometimes hard strips can be felt in the rectal wall, the internal orifice is often near the dentate line or the lower part of the rectum, small hard nodes can be felt by finger palpation, the central depression of the hard nodes is the internal orifice, this depression is mostly on the posterior median line of the anal canal or slightly to one side.
(2) Internal blind fistula, there is often anal pain during defecation, and pus flows from the anus, the fistula is in the rectal wall, and the finger palpation can touch the obvious hard nodes.
11.Treatment.
The treatment of anal fistula is divided into non-surgical and surgical therapies.
The purpose of non-surgical treatment is to control the infection, reduce symptoms and control the development, but it cannot be completely cured or relatively cured for a while, and it is easy to relapse.
(l) Drug therapy.
(2) Topical medication.
(3) Topical ointment.
(4) Herbal treatment.
The purpose of surgical treatment is to completely remove the infected anal glands and remove the infected foreign body from the fistula, which is the key to treatment. However, for fistulas that infringe on the function of the anal sphincter, especially for those with lesions involving the anorectal ring, they must be treated correctly in order to avoid the sequelae of anal incontinence.
(1) Incision method.
(2) Incisional suture method.
(3) incision and hanging method.
12.Treatment tips.
(1) Open the wound to facilitate drainage.
(2) All anal fistula incisions should be radial in shape.
(3) Protect the physiological function of the anus.
(4) The sphincter on the surface of the fistula must be cut when the canal is incised, but if the fistula passes through the rectal ring of the anal canal, it should be treated correctly to prevent anal incontinence. If the fistula travels above the deep external sphincter and cannot be preserved, it should be slowly cut off using Chinese medicine hanging thread therapy.
(5) The deep fistula passes above the anorectal ring and the anorectal ring is not fibrotic, the fistula should never be cut all at once so as not to damage the anorectal ring, but should be cut by hanging wires in the anorectal ring. If the anorectal ring is fibrotic, it can be cut directly vertically and will not cause complete anal incontinence.
(6) If the caudal ligament needs to be cut, it can only be cut longitudinally, not transversely. If the caudal ligament needs to be cut transversely, the severed end of the ligament must be re-sutured and fixed to avoid causing anal collapse and forward displacement.
13. Issues to be noted in the treatment of high anal fistula.
(1) About the treatment of the internal opening.
(2) Pay attention to the principle of drug exchange for the transformation of rot and muscle.
(3) Pay attention to the flow of drainage to prevent granuloma edema.